Gas floated workpiece supporting apparatus and noncontact workpiece support method

ABSTRACT

An apparatus for conveying a substrate includes a base along which the substrate is conveyed, a first upward gas ejecting section, a second upward gas ejecting section and a third upward gas ejecting section disposed over the base, the third upward gas ejecting section being disposed between the first and second upward gas ejecting sections, and a first downward gas ejecting section and a second downward gas ejecting section disposed above and facing respective portions of the third upward gas ejecting section. Gas ejected upward from the first, second and third upward gas ejecting sections floats the substrate. The substrate is subjected to pressure by gas ejected downward from the first and second downward gas ejecting sections. The first and second downward gas ejecting sections are spaced to provide a working area therebetween and through which the substrate is irradiated with a laser beam.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation application of U.S. patentapplication Ser. No. 15/553,990, filed Aug. 26, 2017, which is a U.S.National Phase application of International Patent Application No.PCT/JP2016/054088, filed Feb. 12, 2016, which is based on and claimspriority to Japanese Patent Application No. JP 2015-039050, filed Feb.27, 2015. The entire contents of all the above-identified applicationsare incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a gas floated workpiece supportingapparatus and a noncontact workpiece support method that float aplate-shaped workpiece such as a glass substrate by ejection of gas in anoncontact manner.

BACKGROUND ART

Several proposals have been made for apparatuses that float plate-shapedworkpieces of a glass substrate and the like by gas ejection so far.

For example, Patent Literature 1 proposes a floatation suction mixturesection 50 that is provided with a porous block 51 generating a positivepressure and a suction block 52 generating a negative pressurerespectively on a base, as illustrated in FIG. 7, (A). In the porousblock 51, air is supplied, and the air is ejected from a top surface ofa porous body to hold a plate-shaped workpiece 100 formed of a glasssubstrate in a noncontact state. At the same time, a suction force isworked in the suction block 52 to draw the glass substrate 100 to a topsurface side of the floatation suction mixture section 50. By harmony ofthe suction force and the aforementioned floating force, the glasssubstrate 100 floats with a substantially fixed floating amount withrespect to the top surface of the floatation suction mixture section 50,and a stable floating state is obtained.

Further, as illustrated in FIG. 8, (A), in Patent Literature 2, theplate-shaped workpiece 100 floated above a flotation device 60 ischucked and conveyed in arrow directions with a conveying device notillustrated. In the flotation device 60, air is ejected from entiresurfaces of porous plates 61, and the entire surfaces of the porousplates 61 become air bearing surfaces, so that it becomes possible tofloat the plate-shaped workpiece 100 without causing a warp, and conveythe plate-shaped workpiece 100 without contacting the porous plates 61.Further, in a suction hole 62, a force that sucks the plate-shapedworkpiece 100 is generated. The suction force regulates a floatationamount of the plate-shaped workpiece 100 that is floated by the airejected from the porous plate 61. Accordingly, by controlling thesuction force, it becomes possible to control the floatation amount ofthe plate-shaped workpiece 100.

CITATION LIST Patent Literature

-   [Patent Literature 1] Japanese Patent Laid-Open No. 2006-266351-   [Patent Literature 2] Japanese Patent Laid-Open No. 2008-110852

SUMMARY OF INVENTION Technical Problem

However, in the apparatus shown in Patent Literature 1, the area thatgenerates a positive pressure and the area that generates a negativepressure are in different blocks, so that the floating force isgenerated in the positive pressure area, and the suction force isgenerated in the negative pressure area individually. Consequently, whenthe floating amounts of the substrate over the positive pressuregenerating block and the negative pressure generating block arecompared, a certain difference in floating amount occurs, and when seenas the entire glass substrate as illustrated in FIG. 7, (B), flatness islow in reality. Consequently, when flatness of the entire surface of thesubstrate or a part of the substrate needs to be high in the process ofperforming processing to the entire surface of the substrate or the partof the substrate, the apparatus has the problem of being unable tosatisfy the condition.

Further, in the apparatus illustrated in Patent Literature 2, devicesare made so that the difference does not arise in floating amount on thepositive pressure generating area (porous plate) and the negativepressure generating area (suction hole) in terms of the internalstructure, but in reality, at the time of a large glass substratefloating across a plurality of flotation devices, it is difficult forair to escape in a central portion of the glass substrate as illustratedin FIG. 8, (B), depending on how the flotation devices are arranged.This generates the phenomenon in which an air pool is generated by thepositive pressure that is generated from the porous plate, the substratecentral portion is raised, and flatness of the entire glass substratebecomes low. In order to eliminate the phenomenon, there are cited themethod of disposing many suction holes in the central portion of theglass substrate, but it becomes the problem that the central portion isnot fixed because the glass is conveyed and the optimum layout of thesuction holes changes depending on the glass size.

The present invention is made to solve the problems of the conventionalapparatuses as described above, and one of the objects of the presentinvention is to provide a gas floated workpiece supporting apparatus anda noncontact workpiece support method that unify a floating amount of anentire surface of a plate-shaped workpiece of a glass substrate or thelike, and can increase flatness of the plate-shaped workpiece.

Solution to Problem

To be more specific, a gas floated workpiece supporting apparatus of oneaspect of the present invention includes a gas upward ejector ejectinggas upward, and a gas downward ejector located at an upper side from thegas upward ejector and ejecting gas downward,

wherein the gas downward ejector is installed at a position where thegas downward ejector ejects the gas downward from above a plate-shapedworkpiece and applies pressure, to the plate-shaped workpiece that isfloated and supported by the gas ejected from the gas upward ejector.

According to the above-described present invention, the plate-shapedworkpiece is sandwiched by gas ejection from above, and gas ejectionfrom below, the plate-shaped workpiece can be stably supported in anoncontact manner, and flatness of the plate-shaped workpiece can beenhanced.

The gas floated workpiece supporting apparatus of another aspect of thepresent invention is the aforementioned invention, wherein a part or awhole of the gas downward ejector is installed to correspond to a wholeor a part of a region where the gas upward ejector is installed.

According to the above-described present invention, the gas downwardejector can be disposed in accordance with the gas upward ejector, orthe gas upward ejector can be disposed in accordance with the gasdownward ejector, the plate-shaped workpiece can be favorably sandwichedby the gas in a desired area, and flatness of the plate-shaped workpiececan be increased.

The gas floated workpiece supporting apparatus of another aspect of thepresent invention is the aforementioned present invention, wherein thegas downward ejector is installed except for a working area for theplate-shaped workpiece.

According to the present invention, by disposing the gas downwardejector in an area except for the working area, the predetermined workcan be smoothly performed.

Further, by the working method (process) of the plate-shaped workpiece,the floating amount and floating rigidity of the workpiece can beadjusted.

The gas floated workpiece supporting apparatus of another aspect of thepresent invention is the aforementioned present invention, wherein thegas downward ejector is installed in accordance with part of a regionwhere the gas upward ejector is installed, with a working area for theplate-shaped workpiece sandwiched between the gas downward ejector andthe gas upward ejector.

According to the above-described present invention, by sandwiching theplate-shaped workpiece located in the working area by gas from bothsides, the flatness of the plate-shaped workpiece in the working area isincreased, and precise work is enabled.

In the process of performing work to a part of the plate-shapedworkpiece, not only the entire surface but also the vicinity of aworking point is included as the structure of the present invention,whereby the structure that obtains a uniform floating amount can be madewith respect to a part of the plate-shaped workpiece. The floatingamount and the floating rigidity at this time can be arbitrarily set byadjusting the flow rate and pressure of the pressurized gas from the gasdownward ejector, and the flow rate and the pressure of the pressurizedgas from the gas upward ejector. Further, pressure is applied to theplate-shaped workpiece from upward and downward directions, so that theforce that corrects the plate-shaped workpiece to be flat is generatedespecially in the vicinity of the working area.

The gas floated workpiece supporting apparatus of another aspect of thepresent invention is the aforementioned present invention, and furtherincludes a position adjusting section that adjusts blowout positionspartially or entirely with respect to one or both of a plurality of gasupward ejection holes provided in the gas upward ejector and a pluralityof gas downward ejection holes provided in the gas downward ejector.

According to the above-described present invention, it becomes possibleto adjust pressure applied to the plate-shaped workpiece and change thefloating position by adjustment of the blowout position by the positionadjusting section.

The gas floated workpiece supporting apparatus of another aspect of thepresent invention is the aforementioned present invention, wherein theposition adjusting section is capable of position adjustmentindividually for each of ejection holes positions of which areadjustable, or every predetermined number of ejection holes.

According to the above-described present invention, by adjustment tosome of the ejection holes, a warp and a curve of the plate-shapedworkpiece can be precisely corrected.

The gas floated workpiece supporting apparatus of another aspect of thepresent invention is the aforementioned present invention, and furtherincludes a gas flow adjusting section that adjusts a gas blowout flowrate and/or pressure, with respect to a plurality of gas upward ejectionholes provided in the gas upward ejector, and a part or all of aplurality of gas downward ejection holes provided in the gas downwardejector.

According to the above-described present invention, it is possible toadjust the pressure which is applied to the plate-shaped workpiece andchange the floating position by adjustment of the blowout flow rate andor pressure by the gas flow adjusting section.

The gas floated workpiece supporting apparatus of another aspect of thepresent invention is the aforementioned present invention, wherein thegas flow adjusting section is capable of adjusting a gas blowout flowrate and/or pressure individually for each of ejection holes gas flowsof which are adjustable, or every predetermined number of ejectionholes.

According to the above-described present invention, a warp and a curveof the plate-shaped workpiece can be precisely corrected by adjustmentto some of the ejection holes.

The gas floated workpiece supporting apparatus of another aspect of thepresent invention is the aforementioned present invention, and furtherincludes a control section that controls an adjustment amount of theposition adjusting section at a time of floating and supporting theplate-shaped workpiece.

According to the above-described present invention, adjustment of theposition adjusting section can be performed dynamically by operation ofthe control section.

The gas floated workpiece supporting apparatus of another aspect of thepresent invention is the aforementioned present invention, and furtherincludes a control section that controls an adjustment amount of the gasflow adjusting section at a time of floating and supporting theplate-shaped workpiece.

According to the above-described present invention, adjustment of thegas flow adjusting section can be performed dynamically by operation ofthe control section.

The gas floated workpiece supporting apparatus of another aspect of thepresent invention is the aforementioned present invention, and furtherincludes a detection section that detects a height position of theplate-shaped workpiece, wherein the control section controls theadjustment amount based on a detection result of the detection section.

According to the above-described present invention, stable support andhigh flatness can be obtained by controlling the position adjustingsection and the gas flow adjusting section, in accordance with the stateof the plate-shaped workpiece.

The gas floated workpiece supporting apparatus of another aspect of thepresent invention is the aforementioned present invention, wherein someor all of a plurality of downward ejection holes provided in the gasdownward ejector are overlaid on a plurality of upward ejection holesprovided in the gas upward ejector, in mutual blowout directions.

According to the above-described present invention, the positions of thedownward ejection holes are overlaid on the positions of the informationejection holes in the blowout directions, whereby the plate-shapedworkpiece can be favorably sandwiched with upper and lower pressures.

A noncontact workpiece support method of one aspect of the presentinvention is such that gas is ejected to the plate-shaped workpiece fromabove and below a plate-shaped workpiece respectively, and theplate-shaped workpiece is floated and supported in a noncontact mannerwhile the plate-shaped workpiece is sandwiched by the gas.

The noncontact workpiece support method of another aspect of the presentinvention is the aforementioned present invention, wherein a warp and acurve of the plate-shaped workpiece are corrected to flatten theplate-shaped workpiece, by adjusting one or both of a gap amount ofejection positions of gas to the plate-shaped workpiece, and a flow rateof the gas.

Advantageous Effects of Invention

More specifically, according to the present invention, the plate-shapedworkpiece is floated by ejecting gas to an arbitrary surface (the entireor a part of the surface) of the plate-shaped workpiece from the upwardand downward directions, so that uniform forces are applied to thearbitrary surface of the plate-shaped workpiece, an equivalent floatingamount is obtained on the entire arbitrary surface of the plate-shapedworkpiece, and further there is provided the effect of correcting a warpand a curve of the arbitrary surface of the plate-shaped workpiece toflatten the surface, by the forces.

BRIEF DESCRIPTION OF DRAWINGS

The above and other objects, advantages and features of the presentinvention will become more fully understood from the detaileddescription given herein below and the appended drawings which are givenby way of illustration only, and thus are not intended as a definitionof the limits of the present invention, and wherein:

FIG. 1 is a diagram illustrating a gas floated workpiece supportingapparatus of one embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a distance of a gasupward ejector and a plate-shaped workpiece undersurface, and a forceper unit volume by gas ejection of the gas upward ejector and a load onthe plate-shaped workpiece per unit area, of the embodiment of thepresent invention.

FIG. 3 is a graph showing a relationship between a distance of a gasdownward ejector and a plate-shaped workpiece top surface, and a forceper unit volume by gas ejection of the gas downward ejector, of theembodiment of the present invention.

FIG. 4 is a graph showing a relationship between a distance of the gasupward ejector and the plate-shaped workpiece undersurface, and theforce per unit area by gas ejection of the gas upward ejector and theforce per unit area by gas ejection of the gas downward ejector.

FIG. 5 is a diagram illustrating a gas floated workpiece supportingapparatus of Embodiment 2 of the present invention.

FIG. 6 is a diagram illustrating in (A) a gas floated workpiecesupporting apparatus, and in (B) a partial enlarged diagram of a stage2E of Embodiment 3 of the present invention.

FIG. 7 is illustrating in (A) a floatation apparatus in PatentLiterature 1, and in (B) illustrating a problem of the floatationapparatus.

FIG. 8 is illustrating in (A) a floatation apparatus in PatentLiterature 2, and illustrating in (B) a problem of the floatationapparatus.

DESCRIPTION OF EMBODIMENTS Embodiment 1

Hereunder, one embodiment of the present invention will be describedbased on the accompanying drawings.

In a gas floated workpiece supporting apparatus 1, a stage 2A configuredto float a workpiece at an upper portion side, and a stage 2B configuredto float a workpiece at a lower portion side are installed face-to-facewith a space left vertically.

The stage 2A has a gas downward ejector 3A formed of a porous body inwhich a number of holes are opened in an undersurface, and a base 4Athat is located on an upper part of the gas downward ejector 3A, and thebase 4A is mounted to a stage mounting base 5A that is located on anupper part of the base 4A. Respective holes of the gas downward ejector3A correspond to gas downward ejection holes of the present invention.

The stage 2B has a gas upward ejector 3B formed of a porous body inwhich a number of holes are opened in a top surface and a base 4B thatis located on a lower part of the gas upward ejector 3B, and the base 4Bis mounted to a stage mounting base 5B that is located on a lower partof the base 4B. Respective holes of the gas upward ejector 3B correspondto gas upward ejection holes of the present invention.

The stage mounting bases 5A and 5B are disposed in a vertical direction,whereby surfaces of the respective ejectors of the stages 2A and 2B areconfigured to face each other. Thereby, the gas downward ejection holesare overlaid on the gas upward ejection holes in blowout directions.

The stage mounting base 5A is mounted to a height adjusting mechanism 6that is movable along a Z-axis stage, and capable of adjustment of aheight position. By adjustment of the height adjusting mechanism 6, aheight position, that is, a blowout position of the gas downward ejector3A is changed. The height adjusting mechanism 6 corresponds to aposition adjusting section of the present invention. By an operation ofthe height adjusting mechanism 6, a gap L between the stages 2A and 2Bcan be adjusted.

An air supply pipe 7A communicating with the gas downward ejector 3A isconnected to the base 4A, and the air supply pipe 7A is connected to apressurized gas supplying section not illustrated via a flow controlvalve 8A. The flow control valve 8A can adjust a flow rate and pressureof gas that is supplied to the gas downward ejector 3A through the airsupply pipe 7A. That is, the flow control valve 8A corresponds to a gasflow adjusting section of the present invention.

Further, an air supply pipe 7B communicating with the gas upward ejector3B is connected to the base 4B, and the air supply pipe 7B is connectedto the pressurized gas supplying section not illustrated via a flowcontrol valve 8B. The flow control valve 8B can adjust a flow rate andpressure of gas that is supplied to the gas upward ejector 3B throughthe air supply pipe 7B. That is, the flow control valve 8B correspondsto a gas flow adjusting section of the present invention.

In the gas downward ejector 3A and the gas upward ejector 3B whichreceive supply of gas from the air supply pipes 7A and 7B, flow pathsare provided to eject pressurized gas from the gas downward ejectionholes and the gas upward ejection holes on entire surfaces. The gasdownward ejector 3A and the gas upward ejector 3B need to ejectpressurized gas uniformly from the entire surfaces, and therefore aredesirably formed of porous bodies, but do not always have to be formedof porous bodies, if only the gas downward ejector 3A and the gas upwardejector 3B are ejectors having equivalent performance.

Further, the gas floated workpiece supporting apparatus 1 has a controlsection 9 that controls the height adjusting mechanism 6, and the flowcontrol valves 8A and 8B. The control section 9 is configured by a CPU,a program that operates the CPU, a storage section such as a nonvolatilememory and a RAM. The control section 9 can adjust the height adjustingmechanism 6 and the flow control valves 8A and 8B by initial setting,and can perform control of dynamically adjusting the height adjustingmechanism 6 and the flow control valves 8A and 8B during noncontactsupport. Further, control of adjusting the height adjusting mechanism 6,the flow control valves 8A and 8B can be performed based on a detectionresult for a plate-shaped workpiece 100 that is supported in anoncontact manner, by a height detecting section not illustrated.

The plate-shaped workpiece 100 is installed between the upper and lowerstages 2A and 2B. In the present embodiment, the plate-shaped workpieceis described as a glass substrate. A size of the plate-shaped workpiece100 in Embodiment 1 is a size that is within a range of the top surfaceof the gas upward ejector 3B of the stages 2A and 2B.

Here, pressurized gas is supplied to the upper and lower stages 2A and2B through the air supply pipes 7A and 7B. In Embodiment 1, as thepressurized gas, gas such as air, clean dry air, and N2 can be used. Asthe present invention, the kind of gas is not especially limited.

Pressure and a flow rate of the pressurized gas that is supplied to theupper and lower stages 2A and 2B can be controlled by the flow controlvalves 8A and 8B respectively. When the pressurized gas is supplied tothe upper and lower stages 2A and 2B, the pressure and the flow rate areadjusted by the flow control valves 8A and 8B, and the pressurized gasat arbitrary pressure and flow rate is ejected by the gas downwardejector 3A and the gas upward ejector 3B. The pressurized gas ejectedfrom the gas downward ejector 3A of the upper stage 2A is ejected to atop surface of the plate-shaped workpiece 100. The pressurized gasejected from the gas upward ejector 3B of the lower stage 2B is ejectedto an undersurface of the plate-shaped workpiece 100. An ejecting forceof the pressurized gas ejected to the top surface and the undersurfaceof the plate-shaped workpiece 100 are balanced, and the plate-shapedworkpiece 100 is uniformly floated in the entire surface.

Hereunder, a relationship between the ejecting force of the pressurizedgas and a floating amount will be described.

FIG. 2 shows a relationship between a gap Lu between the stage 2A andthe glass substrate as the plate-shaped workpiece 100, and a force Fu[gf/cm2] per unit area that is given to the top surface of the glasssubstrate by the pressurized gas ejected from the gas downward ejector3A of the stage 2A, when an arbitrary application pressure Pu [kPa] isapplied to the stage 2A in FIG. 1. A gradient and an intercept of agraph and a flow rate Qu [L/min] vary in accordance with a kind of theporous body (a pore diameter and a pore rate). Further, when a load perunit area of the glass substrate is set as Fg, a magnitude of a forcethat is balanced with the force that is finally ejected to theundersurface of the gas substrate from the stage 2B side is Fu+Fg[gf/cm2]. Hereinafter, the force will be referred to as a gravitydirection force Fu+Fg.

FIG. 3 shows a relationship between a gap Ld [μm] between the stage 2Band the glass substrate as the plate-shaped workpiece 100, and a forceFd [gf/cm2] per unit area that is given to the undersurface of the glasssubstrate by the pressurized gas ejected from the gas upward ejector 3Bof the stage 2B, when arbitrary application pressure Pd [kPa] is appliedto the stage 2B in FIG. 1. A gradient and an intercept of the graph anda flow rate Qd [L/min] vary in accordance with the kind of the porousbody (the pore diameter and the pore rate). Hereinafter, the force Fdwill be referred to as the antigravity direction force Fd.

When the gravity direction force Fu+Fg and the force Fd are equal toeach other, the forces are balanced, and the glass substrate floats.

When a gap between the stages 1A and 1B is set as L, the gap between theundersurface of the gas downward ejector 3A and the top surface of theglass substrate is set as Lu, and the gap between the top surface of thegas upward ejector 3B and the undersurface of the glass substrate is setas Ld, and the thickness of the glass substrate is set as Lg, L isexpressed by

|L|=|Lu|+|Lg|+|Ld|.

Here, the gravity direction force Fu+Fg is applied to the top surface ofthe glass substrate, and the antigravity direction force Fd is appliedto the undersurface of the glass substrate.

|Lu|≤|L|−|Lg|=|Lu|+|Ld|

|Ld|≤|L|−|Lg|=|Lu|+|Ld|

Consequently, the forces in the opposite directions are regarded asbeing applied to the same range, so that when the antigravity directionis set as a normal direction, in FIG. 4 where FIG. 2 is reversed andFIG. 3 is overlaid on reversed FIG. 2, a value on an X axis of anintersection point of the graph of the gravity direction force (Fu+Fg)and the graph of the antigravity direction force Fd corresponds to thefloating amount, and the floating amount is the same with respect to theentire surface of the glass substrate, that is, the floating amount isfixed.

Further, when the value on the Y-axis at the intersection point is seen,the value represents the force given to the unit areas of the upper andlower surfaces of the glass substrate, and the plate-shaped workpiece isin the state pressed by the force from up and down. That is, the glasssubstrate is in the state where the entire upper and lower surfaces arepressed with air, and this becomes a substrate correcting force thatcorrects the glass substrate to be flat.

Further, when the floating amount changes by a temporary disturbance,for example, when the floating amount becomes small, Fu+Fg becomessmall, and Fd becomes large. Consequently, the antigravity directionforce>gravity direction force is established, so that the force pushesup the glass substrate, and returns to a balance point. When thefloating amount becomes large, Fu+Fg becomes large, and Fd becomessmall. Consequently, the gravity direction force>antigravity directionforce, and the force presses down the glass substrate and returns to thebalance point. The force to return to the balance point, namely,floating rigidity varies depending on an intersection angle θ in thegraph of the force in the gravity direction and the force in theantigravity direction in the balance point. As the intersection angle θis larger, the floating rigidity is higher, whereas as the intersectionangle θ is smaller, the floating rigidity is lower.

In the present embodiment, by changing a gap of the pressures that areapplied to the stages configured to float a workpiece, and the kind ofthe flotation devices, the distances between the stages and theplate-shaped workpiece, and the flow rate and the pressure of gasejection are changed, and the floating amount, the substrate correctingforce and the floating rigidity described above can be arbitrarily set.

In the above-described embodiment, the air supply pipes 7A and 7B arerespectively connected to the gas downward ejector 3A and the gas upwardejector 3B respectively, and in each of the gas downward ejector 3A andthe gas upward ejector 3B, the gas flow rate and the pressure are madeadjustable. However, each of the gas downward ejector 3A and the gasupward ejector 3B is divided into a plurality of areas, and the gas flowrate and the pressure can be made adjustable in each of the areas, orthe gas flow rate and the pressure can be made adjustable for each ofthe individual ejection holes. Further, a configuration can be adoptedin which adjustment of only either one of the gas flow rate and pressureis performed.

Second Embodiment

In Embodiment 1 described above, the gas downward ejector is installedin accordance with the entire gas upward ejector, but the gas downwardejector can be installed in accordance with a part of the gas upwardejector. Embodiment 2 will be described based on FIG. 5. In the drawing,the gas upward ejector can be installed in accordance with a part of thegas downward ejector.

In Embodiment 2, a working area W for the plate-shaped workpiece 100 isprovided, and the gas downward ejector is provided to avoid the workingarea W.

In Embodiment 2, the stage 2B side has similar components to thecomponents in Embodiment 1, so that the similar components are assignedwith the same reference signs, and detailed explanation of the similarcomponents is omitted.

Meanwhile, at an upper part, a stage 2C configured to float a workpieceand a stage 2D configured to float a workpiece are provided to face thestage 2B to avoid the working area W.

The stage 2C is located at one side of the working area W, and has a gasdownward ejector 3C that is formed of a porous body with a number ofholes opened on an undersurface, and a base 4C located at an upper partof the gas downward ejector 3C, and the base 4C is mounted on a stagemounting base 5C located on an upper part of the base 4C. Respectiveholes of the gas downward ejector 3C correspond to the gas downwardejection holes of the present invention.

The stage 2D is located at the other side of the working area W, and hasa gas downward ejector 3D that is formed of a porous body with a numberof holes opened on an undersurface, and a base 4D located at an upperpart of the gas downward ejector 3D, and the base 4D is mounted on astage mounting base 5D located on an upper part of the base 4D.Respective holes of the gas downward ejector 3D correspond to the gasdownward ejection holes of the present invention.

Though not illustrated, the stage mounting base 5C and the stagemounting base 5D are connected, and are mounted to the height adjustingmechanism 6 movable along the Z-axis stage, so that adjustment of heightpositions is enabled. By adjustment of the height adjusting mechanism 6,the height positions, that is, blowout positions of the gas downwardejector 3C and the gas downward ejector 3D are changed. By theoperation, the gap L between the stage 2B, and the stages 2C and 2D canbe adjusted.

Here, it is described that the stage mounting base 5C and the stagemounting base 5D are connected and mounted to the height adjustingmechanism 6, but a configuration can be adopted in which the stagemounting base 5C and the stage mounting base 5D are respectively mountedto independent height adjusting mechanisms, and heights of the stagemounting base 5C and the stage mounting base 5D can be adjustedindependently from each other.

An air supply pipe 7D communicating with the gas downward ejector 3D isconnected to the base 4D, the air supply pipe 7D is connected to apressurized gas supplying section not illustrated through a flow controlvalve 8D. The flow control valve 8D can adjust a flow rate and pressureof the gas that is supplied to the gas downward ejector 3D through theair supply pipe 7D. That is, the flow control valve 8D corresponds tothe gas flow adjusting section of the present invention.

Further, an air supply pipe 7C communicating with the gas downwardejector 3C is connected to the base 4C. The air supply pipe 7C canadjust a flow rate and pressure of gas by the flow control valve 8D bybeing connected to the air supply pipe 7D.

The air supply pipe 7C is not connected to the air supply pipe 7D, and aflow control valve (not illustrated) that is separate from the flowcontrol valve 8D is interposed in the air supply pipe 7C, so that thegas flow rate and the pressure at the air supply pipe 7C side can beadjusted independently from the air supply pipe 7D side.

Further, a gas floated workpiece supporting apparatus 1A has the controlsection 9 that controls the height adjusting mechanism 6, and the flowcontrol valve 8D. The control section 9 is configured by a CPU and aprogram that operates the CPU, and a storage section such as anonvolatile memory and a RAM. The control section 9 can adjust theheight adjusting mechanism 6 and the flow control valve 8D by initialsetting, or can perform control of adjusting the height adjustingmechanism 6 and the flow control valve 8D during noncontact support.

Further, in Embodiment 2, height detecting sections 10 and 11 thatdetect a height of the plate-shaped workpiece is installed in theworking area W so as to be located at both the sides of the working areaW. The height detecting sections 10 and 11 detect a height position ofthe plate-shaped workpiece 100 by using a light sensor, laser or thelike. Detection results of the height detecting sections 10 and 11 aretransmitted to the control section 9, and control of adjusting theheight adjusting mechanism 6 and the flow control valve D can beperformed based on the detection results to the plate-shaped workpiece100 by the height detecting sections 10 and 11.

In Embodiment 2, work such as laser irradiation and exposure to theglass substrate, for example, can be performed through the working areaW. At this time, in an area B, only the force in the antigravitydirection from the stage 2B is applied, and a correcting force to theplate-shaped workpiece 100 is not obtained. However, the plate-shapedworkpiece 100 is corrected to be flat and floats in an area A and anarea C, the plate-shaped workpiece 100 further has rigidity so that theplate-shaped workpiece 100 does not rise greatly only in the area Bportion, and a floating amount that is uniform enough not to exert anadverse effect on working can also be ensured in the area B.

Embodiment 3

In Embodiment 2 described above, the gas downward ejector is installedin accordance with the gas upward ejector except for the working area,but the gas downward ejector can be installed in only a vicinity of theworking area. Embodiment 3 will be described based on FIGS. 6(A) and(B).

In Embodiment 3, flotation devices 20B, 20C and 20D configured to floata workpiece are disposed at a lower side along a conveying direction ofthe plate-shaped workpiece 100. The plate-shaped workpiece 100 isconveyed in an illustrated conveying direction in a noncontact state bya conveying device 15.

The stage 20B has a gas upward ejector 23B formed of a porous body witha number of holes opened on a top surface and a base 24B located on alower part of the gas upward ejector 23B. The stage 20C has a gas upwardejector 23C formed of a porous body with a number of holes opened on atop surface and a base 24C located on a lower part of the gas upwardejector 23C. The stage 20D has a gas upward ejector 23D formed of aporous body with a number of holes opened on a top surface and a base24D located on a lower part of the gas upward ejector 23D. The bases24B, 24C and 24D are commonly mounted to the stage mounting base 5Blocated on lower parts of the bases 24B, 24C and 24D. The respectiveholes of the gas upward ejectors 23B, 23C and 23D correspond to the gasupward ejection holes of the present invention.

Meanwhile, on an upper side, in positions sandwiching the working areaW, a stage 2E and a stage 2F configured to float a workpiece areinstalled in accordance with a region of the stage 20C.

The stage 2E is located at one side of the working area W, and has a gasdownward ejector 3E formed of a porous body opened on an undersurfaceand a base 4E located on an upper part of the gas downward ejector 3E.The base 4E is mounted to a stage mounting base 5E located on an upperpart of the base 4E. Respective holes of the gas downward ejector 3Ecorrespond to the gas downward ejection holes of the present invention.

The stage 2F is located at the other side of the working area W, and hasa gas downward ejector 3F formed of a porous body opened on anundersurface and a base 4F located on an upper part of the gas downwardejector 3F. The base 4F is mounted to a stage mounting base 5F locatedon an upper part of the base 4F. Respective holes of the gas downwardejector 3F correspond to the gas downward ejection holes of the presentinvention.

Though not illustrated in the drawings, the stage mounting base 5E andthe stage mounting base 5F are connected and are mounted to the heightadjusting mechanism 6 movable along the Z-axis stage, and adjustment ofa height position is enabled. Height positions, that is, the blowoutpositions of the gas downward ejector 3E and the gas downward ejector 3Fare changed by adjustment of the height adjusting mechanism 6. By theoperation, the gap L between the stage 20C, and the stages 2E and 2F canbe adjusted.

Here, it is described that the stage mounting base 5E and the stagemounting base 5F are connected and are mounted to the height adjustingmechanism 6, but a configuration can be adopted, in which the stagemounting base 5E and the stage mounting base 5F are respectively mountedto independent height adjusting mechanisms and heights thereof can beadjusted individually.

Air supply pipes not illustrated that communicate with the gas downwardejectors 3E and 3F are connected to the bases 4E and 4F. In the airsupply pipes, a flow control valve as a flow adjusting section can beprovided as in the aforementioned embodiments, and gas flow rates andpressures can be made adjustable individually by providing an air supplypipe and a flow adjusting section for each of the bases 4E and 4F.

Further, in a gas floated workpiece supporting apparatus 1B, a controlsection that controls the height adjusting mechanism 6 and the flowcontrol valve can be provided to control operations. At that time, aheight detecting section that detects a height of the plate-shapedworkpiece is installed in the working area W, a detection result of theheight detecting section is transmitted to the control section and theabove-described control can be performed.

In Embodiment 3, the plate-shaped workpiece 100 is corrected to be flatonly in a region in the vicinity of a working point, and floating withhigh precision can be realized.

Embodiment 3 has the conveying device 15 that conveys the plate-shapedworkpiece 100 along the illustrated conveying direction as describedabove. The conveying device 15 grasps a part of the plate-shapedworkpiece 100 to give a moving force along the conveying direction, andperforms conveyance by pushing from a rear side in the conveyingdirection, pulling from a front side in the conveying direction and thelike. Further, the mechanism that conveys the plate-shaped workpiece 100by pressure of gas can be adopted. As the present invention, aconfiguration of the conveying device is not specially limited, and theconfiguration that can convey an object to be conveyed that is floatedby gas can be adopted.

The plate-shaped workpiece 100 is conveyed in a noncontact manner alongthe conveying direction illustrated in FIG. 6 over the stage 20Bconfigured to float a workpiece.

At this time, at an upstream side in the conveying direction, theplate-shaped workpiece 100 only floats by pressurized gas ejected fromthe stage 20B, so that the plate-shaped workpiece 100 is not correctedto be flat, and precision of the floating amount of the plate-shapedworkpiece 100 is low.

Thereafter, the plate-shaped workpiece 100 is conveyed over the stage20B to a downstream side, and enters between the stages 2E and 20C. Inorder to make it easier for the plate form work 100 to enter between thestages 2E and 20C at this time, work such as a tapered portion T can beperformed at an upstream side in the conveying direction of the gasdownward ejector 3E of the stage 2E so that a distance from theplate-shaped workpiece 100 becomes larger toward an upstream end.Thereby, when the plate-shaped workpiece 100 enters between the stages2E and 20C, variation of the pressure from above can be decreased todecrease swing or the like of the plate form work 100. Further, asimilar operation can be obtained by making the flow rate and pressureof the gas lower at the upstream side in the conveying direction of thegas downward ejector 3E than at the downstream side in the conveyingdirection of the gas downward ejector 3E.

The plate-shaped workpiece 100 obtains a floating amount with highprecision in the region between the stages 2E and 20C according to thefloating principle shown in Embodiment 1. When conveyance progresses,the plate-shaped workpiece 100 is floated and supported by only thestage 20D, from the region between the stages 2E and 20C. Correction isnot performed in the region, and support with low precision isperformed.

According to Embodiment 3, the plate-shaped workpiece can be floatedwith high precision in the vicinity of the working point (region forworking purpose), and in the region except for the region for workingpurpose (region for the purpose of only conveyance), the plate-shapedworkpiece can be floated to such an extent that the plate-shapedworkpiece can be conveyed without contacting the stages by thepressurized gas ejected from the stages 20B and 20D, so that theapparatus structure is simplified and apparatus cost can be reduced. InEmbodiment 3, the plate-shaped workpiece can be conveyed by beingsupported in a noncontact manner, irrespective of the size of the plateform work.

The present invention has been described thus far based on theabove-described respective embodiments, and arbitrary changes can bemade without departing from the scope of the present invention.

REFERENCE SIGNS LIST

-   1 Gas floated workpiece supporting apparatus-   1A Gas floated workpiece supporting apparatus-   1B Gas floated workpiece supporting apparatus-   2A stage-   2B stage-   2C stage-   2D stage-   2E stage-   2F stage-   3A Gas downward ejector-   3B Gas downward ejector-   3C Gas downward ejector-   3D Gas downward ejector-   3E Gas downward ejector-   3F Gas downward ejector-   6 Height adjusting mechanism-   7A Air supply pipe-   8A Flow control valve-   7B Air supply pipe-   8B Flow control valve-   8D Flow control valve-   9 Control section-   10 Height detecting section-   11 Height detecting section-   15 Conveying device-   20B stage-   20C stage-   20D stage-   23B Gas upward ejector-   23C Gas upward ejector-   23D Gas upward ejector-   W Working area-   T Tapered portion

1. An apparatus for conveying a substrate, the apparatus comprising: abase along which the substrate is conveyed; a first upward gas ejectingsection, a second upward gas ejecting section and a third upward gasejecting section disposed over the base, the third upward gas ejectingsection being disposed between the first and second upward gas ejectingsections; and a first downward gas ejecting section and a seconddownward gas ejecting section disposed above and facing respectiveportions of the third upward gas ejecting section, wherein: gas ejectedupward from the first, second and third upward gas ejecting sectionsfloats the substrate, the substrate is subjected to pressure by gasejected downward from the first and second downward gas ejectingsections, and the first and second downward gas ejecting sections arespaced to provide a working area therebetween and through which thesubstrate is irradiated with a laser beam.
 2. The apparatus according toclaim 1, wherein floating height of the substrate above the third upwardgas ejecting section is controlled with higher precision than floatingheight of the substrate above the first and second upward ejectingsections.
 3. The apparatus according to claim 1, wherein pressures ofupward and downward ejected gases are balanced to stabilize thesubstrate in a vertical direction above the third upward gas ejectingsection.
 4. The apparatus according to claim 1, wherein the third upwardgas ejecting section has a porous main surface through which gas isejected upward.
 5. The apparatus according to claim 1, wherein: thesubstrate is conveyed in a direction from the first downward gasejecting section to the second downward gas ejecting section, a mainsurface of the first downward gas ejecting section has two end portions,one of the two end portions is farther from the second downward gasejecting section than another of the two end portions, and the one ofthe two end portions is tapered.
 6. The apparatus according to claim 1,further comprising a height adjusting mechanism configured to move thefirst and second downward gas ejecting sections in a vertical direction.7. The apparatus according to claim 1, further comprising flow controlvalves disposed to control flow rates and pressures of the upward andthe downward ejected gases.
 8. The apparatus according to claim 1,further comprising a height detector configured to detect a floatingheight of the substrate, wherein a flow rate and a pressure of each ofthe upward gas and the downward gas are controlled based on the floatingheight detected by the height detector.
 9. The apparatus according toclaim 1, wherein the upward gas is air or nitrogen.
 10. The apparatusaccording to claim 1, wherein the downward gas is air or nitrogen. 11.The apparatus according to claim 1, wherein the substrate is comprisedof glass.